CN101662247B - Current-limiting soft-starting method of asynchronous motor under wideband power supply - Google Patents
Current-limiting soft-starting method of asynchronous motor under wideband power supply Download PDFInfo
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- CN101662247B CN101662247B CN2009101876661A CN200910187666A CN101662247B CN 101662247 B CN101662247 B CN 101662247B CN 2009101876661 A CN2009101876661 A CN 2009101876661A CN 200910187666 A CN200910187666 A CN 200910187666A CN 101662247 B CN101662247 B CN 101662247B
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Abstract
The invention relates to a current-limiting soft-starting method of an asynchronous motor under wideband power supply; by adopting multi-level frequency-division current-limiting soft starting, according to Ua, Ub and Uc synchronizing signals, the power generating frequency of a power generator and effective value of current, the conducting moment and conducting time of all silicon controlled rectifiers are determined, and when the rotating speed difference of the synchronous rotating speed and practical rotating speed of the motor is no more than the setting value of the rotating speed difference, a bypass contactor of a main loop is closed, and direct driving is carried out. The method has the advantages of simple structure, small volume, light weight, convenient maintenance, good performance, high reliability and good economical efficiency.
Description
Technical field
The invention belongs to the diesel locomotive technical field, relate in particular to the current-limiting soft-starting method of asynchronous motor under a kind of wideband power supply.
Background technology
In prior art, the driving method of diesel locomotive cooling fan has hydrostatic transmissions, jumps multiple modes such as the transmission of ripple frequency-changing AC, pole changing and inverter frequency control.
The hydrostatic transmissions mode is that drive system connects rear gear box by diesel engine through two universal drive shafts, and rear gear box connects hydrostatic pump, through the fluid motor-driven cooling fan.This cooling fan driving method has shortcomings such as mechanical breakdown is many, the system maintenance amount big, it is big to take up room, weight is high, efficient is low, less economical; In use; When breaking down, temperature control valve (TCV) can cause the too high fault of diesel coolant temperature (oil temperature); Influence the normal operation of locomotive, therefore traditional cooling fan driving method is the needs of incompatibility modern railways transportation more and more.
Jumping the ripple frequency-changing AC kind of drive is that system partly blocks supply voltage and reconfigures; Produce the electric current cycle of a pulsation and the electromagnetic torque of pulsation; Especially under 1/2 full speed, three-phase voltage vector space angle is distinguished 60 °, 150 °, 150 °, and motor moves under serious asymmetric three-phase voltage; Its overload capacity and efficient reduce; Mis-behave, and part (like a certain phase winding) risk of overheating is arranged, therefore adopt this scheme must improve the capacity and the heat-sinking capability of motor.The electromagnetic torque of pulsation will have a strong impact on the useful life of rotor and bearing in addition.
Thereby the pole changing mode is to change synchronous speed through conversion asynchronous motor winding number of poles to carry out speed governing.In the process that control motor number of pole-pairs changes, three phase mains is not the continuous motor that is supplied to, but cuts off three phase mains earlier, waits for that the back-emf of motor armature winding reduces to zero, carries out pole-changing control through the switching of contactor again.If after cutting off three phase mains; Carry out pole-changing control immediately; The back-emf of input voltage and motor armature winding will produce superposition and very big rush of current occur, even the rush of current when being higher than full rotating speed across-the-line starting, the safety of serious threat machinery and electric equipment.Therefore will cut off three phase mains earlier, wait motor back-emf reduces to zero, carries out pole-changing control again; In the case, when motor when 1/2 changes at full speed at full speed, the rotating speed of fan will be at first because of the decline rapidly that runs out of steam; During pole-changing, impulse current also can be very big.Carry out in addition in the process of pole-changing control, need three A.C. contactors to switch, if adopt two cooling fans of high and low temperature, then need six A.C. contactors, Electric device with a contact increases greatly, is unfavorable for the reliability of system.
The inverter frequency control way can be realized accurate rotating speed control, and the rotating speed of fan motor can be regulated according to the variation of water temperature automatically.Motor starting is soft start, and starting current is little, and operating current increases with the increase of fan rotating speed gradually, and when reaching rated speed, operating current is a rated current, impacts little to electrical equipment and mechanical system.But the input cost of inverter is high, and is very high to the requirement of degree of protection, radiating condition and maintaining.Under the inverter power supply condition, threephase asynchronous voltage is non-sinusoidal waveform, and the high order harmonic component that wherein contains can make motor produce additional copper loss, iron loss and stray loss.Harmonic wave also can cause motor torque ripple, and noise increases.When under the HF switch frequency, moving, can produce tangible kelvin effect in the rotor.Temperature rise when supplementary load loss and kelvin effect make the motor stabilizing operation significantly increases.Two common in addition level and three-level pwm voltage source inverter are because output voltage saltus step step is bigger, and the saltus step of phase voltage reaches the half the of DC bus-bar voltage, can produce bigger dv/dt.Bigger dv/dt can influence the insulation of motor.So to having relatively high expectations of this motor, the cost of motor is also very high.
The cooling fan of diesel locomotive belongs to the fan type load, the size of load torque and rotational speed N square be directly proportional T
L=kn
2, k is a proportionality constant in the formula, the torque characteristic curve of blower fan is as shown in Figure 1.The mechanical characteristic of the asynchronous motor of drive fan is shown in accompanying drawing 2.Through the mechanical characteristic of asynchronous motor and the torque characteristic curve of blower fan are compared; Can find out constant at frequency of supply; Regulate supply power voltage and be raised to gradually the maximum process from zero, the electromagnetic torque of motor is directly proportional for alive square with its winding institute, and the electromagnetic torque of motor also increases gradually; Mechanical property changes software strategy into software-hardware strategy, and this just in time adapts to the characteristic of blower fan torque zero crossing.But; The three-phase fully-controlled rectification of prior art, the trigger impulse of pressure regulation are produced like (TC787DS) by the phase control special chip; Owing to adopt the mode of time scale integration to produce drive pulse signal; The thyristor soft starter device of prior art only adapts to 50Hz or 60Hz decides frequency power, only allows supply frequency among a small circle, to change, because the alternator generation frequency of diesel locomotive changes with diesel engine speed; General diesel engine speed excursion is 400r/mim～1000r/mim, and the generating frequency of alternating current generator is 40%～100% rated frequency.Under the power supply condition of power supply that rated frequency 40%～100% changes, this control mode can't adapt to the requirement of the diesel locomotive cooling fan motor soft start under the variable-frequency variable-voltage condition of power supply.
Summary of the invention
The object of the invention overcomes the deficiency of above-mentioned prior art exactly, provide a kind of simple in structure, volume is little, in light weight, easy to maintenance, function admirable, reliability are high, the current-limiting soft-starting method of asynchronous motor under the wideband power supply of good economy performance.
The objective of the invention is existing like this: the current-limiting soft-starting method of asynchronous motor under a kind of wideband power supply is characterized in that taking following steps:
A. detect Ua, Ub, Uc synchronizing signal;
B. calculate the generating frequency of alternating current generator;
C. calculate the half wave cycles Ta (Ta is full ON time) of three-phase alternating voltage;
D. detect the output current effective value of alternating current generator;
E. maximum current limit value is controlled through the slope, draws the output current limit value, and with output current effective value feedback ratio, its difference is handled through the PID adjuster, draws thyristor ON time Ton (maximum of Ton is Ta);
F. confirm that according to synchronizing signal, Ta, Ton each thyristor conducting constantly;
G. according to the conducting of each thyristor constantly and ON time, generate each thyristor start pulse signal, control the conducting of each thyristor and close;
H. calculate corresponding asynchronous motor synchronous speed under current generating frequency;
I. detect the actual speed of asynchronous motor;
J. synchronous speed and the actual speed with asynchronous motor compares, if speed discrepancy greater than the speed discrepancy set point, then returns step a; Otherwise, get into next step;
K. soft start finishes, and closed major loop bypass contactor transfers direct driving to.
In order to realize the object of the invention better, the current-limiting soft-starting method of asynchronous motor under the said wideband power supply, can further take following steps:
A. confirm maximum frequency division progression and corresponding divider ratio at different levels;
B. the frequency divider stage counter is initialized as 1;
C. confirm corresponding divider ratio according to frequency divider stage counter value;
D. carry out above-mentioned a to j step, wherein: in step f, be constantly and ON time, generate each thyristor gating half-wave start pulse signal, control the conducting of each thyristor and close according to the conducting of the corresponding half-wave of current frequency division gating and each thyristor; In step h, be to calculate pairing asynchronous motor synchronous speed under current generating frequency and crossover frequency; In step j,, then get into step e if speed discrepancy is not more than the speed discrepancy set point;
If E. current frequency divider stage counter value is less than maximum frequency division progression, then frequency divider stage counter value adds 1, returns C; Otherwise, get into above-mentioned steps k.
Adopt method of the present invention; According to predefined starting curve and frequency division progression, increase the angle of flow α of soft starter gating thyristor, the terminal voltage of motor is increased gradually; The supply frequency classification of input motor is risen; Motor smoothly quickens, the growth rate through current limliting closed loop restriction motor terminal voltage simultaneously, thereby when having reduced motor starting to the mechanical shock of generator, motor itself, continuous electric equipment.
Adopt method of the present invention, can realize the level and smooth control of starting current and starting torque, motor can drive fan load starting and stopping at any time, and the temperature of high and low warm water is controlled within the specific limits.In the process that loads, along with the rotating speed of diesel engine is high more, the diesel engine power output is big more, and speed of cooling fan is also high more, and heat-sinking capability is also strong more, and this just meets the requirement of diesel engine cooling.
Method of the present invention is equally applicable to the soft start of locomotive air compressor motor and suction motor, and the torque characteristics of air compressor motor is permanent torque characteristics, and starting torque is big, therefore must adopt multistage frequency division current-limiting soft-starting method.The torque characteristic curve of the torque characteristic curve of suction motor and cooling fan motor is basic identical, and starting torque is little, can adopt one or more levels frequency division current-limiting soft-starting method.
Adopt method of the present invention; Main circuit need only adopt thyristor and simple RC to absorb circuit, and whole main circuit is simple, and the thyristor component reliability is high; Temperature accommodation is wide; Therefore system has simple in structure, characteristics such as volume is little, in light weight, easy to maintenance, function admirable, reliability height, and less demanding to degree of protection, radiating condition and maintaining adapts to the application under the abominable natural conditions such as high temperature, low temperature, dust storm.Cost reduces greatly, economic benefit and obvious social benefit.Because apparatus structure is simple, volume is little, in light weight, the axle that can reduce locomotive is heavy, saves the inner space of locomotive, is beneficial to the modularized design of locomotive.When the soft start end, bypass contactor is connected, and fan electromotor transfers alternating current generator to and directly drives; The supply voltage of threephase asynchronous is sinusoidal wave, and efficient is high, and harmonic content is low; It is little that motor produces additional copper loss, iron loss and stray loss, and the temperature rise of motor significantly reduces.
Description of drawings
Accompanying drawing 1 is the torque characteristic curve of blower fan.
Accompanying drawing 2 is the mechanical characteristic of asynchronous motor.
Accompanying drawing 3 is the main circuit principle schematic of the embodiment of the invention.
Accompanying drawing 4 is the control system theory diagram of the embodiment of the invention.
Accompanying drawing 5 is the computer main program flow block diagram of the embodiment of the invention.
Accompanying drawing 6 is the computer current-limiting soft-starting subprogram FB(flow block) of the embodiment of the invention.
Accompanying drawing 7 is the computer current limliting closed loop subprogram FB(flow block) of the embodiment of the invention.
Embodiment
Specify embodiments of the invention below in conjunction with accompanying drawing.Referring to accompanying drawing 3, in the three-phase main circuit, be connected in series thyristor Q1 and Q2, Q3 and Q4, Q5 and the Q6 of one group of reverse parallel connection respectively, bypass contactor MC is connected across the two ends of respectively organizing thyristor.
Referring to accompanying drawing 4, the motor special DSP ic30f6010A control board that the control system of the embodiment of the invention adopts has characteristics such as execution speed is fast, disposal ability is strong, internal storage space is big, rich interface.It gathers signals such as current effective value, motor speed, three-phase voltage U a, Ub, Uc, generates each thyristor start pulse signal Tr1～Tr6, through pulse power amplifier and pulse transformer, drives each thyristor Q1～Q6; Generate the Do1 signal, through relay output, control bypass contactor MC.
Referring to accompanying drawing 5～accompanying drawing 7, say the control of soft method of the embodiment of the invention in detail below.Referring to accompanying drawing 5, this program is produced regularly by timer interrupts, and every 5ms carries out once.Program gets into frame 2, pick-up transducers, switch, Control on Communication signal by frame 1 beginning.Get into frame 3, confirm maximum frequency division progression and corresponding divider ratio at different levels.For example confirm that maximum frequency division progression is 4, divider ratios at different levels are followed successively by: the 1st grade is 13, the 2 grades is 7, and it is 1 that 3rd level is 4, the 4 grades.Get into frame 4, judge whether starting switch is closed, if not, then get into frame 7, the frequency divider stage counter is initialized as 1, gets into frame 8 then, termination routine; If then get into frame 5.At frame 5, whether judge the main circuit input voltage greater than lower limit, if not, then get into frame 7, the frequency divider stage counter is initialized as 1, get into frame 8 then, termination routine; If, then get into frame 6, call the current-limiting soft-starting subprogram.After the current-limiting soft-starting subprogram executes, get into frame 8, termination routine.
Referring to accompanying drawing 6, the current-limiting soft-starting subprogram gets into frame 6.2 at frame 6.1 inlets, according to the current corresponding divider ratio of frequency counter that draws.Get into frame 6.3 and detect Ua, Ub, Uc synchronizing signal.Get into frame 6.4, according to the corresponding half-wave of current frequency division gating.Get into frame 6.5, calculate the generating frequency of alternating current generator.Calculate the half wave cycles Ta of three-phase alternating voltage.Get into frame 6.7, call current limliting closed loop subprogram, draw each gating thyristor ON time Ton.Get into frame 6.8, confirm that each gating thyristor conducting constantly.Get into frame 6.9, generate each thyristor start pulse signal.Get into frame 6.10, calculate corresponding asynchronous motor synchronous speed Ns under current generating frequency and frequency division.Get into frame 6.11, detect the actual speed N of asynchronous motor.Get into frame 6.12, whether the difference of judging Ns and N is greater than the speed discrepancy set point, if then get into frame 6.16, sub-routine ends; If, then do not get into frame 6.13.At frame 6.13, judge whether maximum frequency division progression equates with the frequency divider stage counter, if not, then get into 6.15, the frequency divider stage counter adds 1; If, then getting into frame 6.14, closed bypass contactor transfers direct driving to, gets into frame 6.16 then, termination routine.
Referring to accompanying drawing 7, current limliting closed loop subprogram gets into frame 6.7.2 at frame 6.7.1 inlet, loads transmission of electricity ductility limit definite value Iref.Get into frame 6.7.3, the output current limit value is carried out slope control.Get into frame 6.7.4, calculate the poor of output current value of feedback and output current limit value.Get into frame 6.7.5, difference between current is carried out PI adjusting computing draw Ton.Get into frame 6.7.6, whether judge Ton, if not, then get into frame 6.7.8, sub-routine ends greater than Ta; If, then get into frame 6.7.7, make Ton equal Ta, get into frame 6.7.8 then, sub-routine ends.
Claims (2)
1. the current-limiting soft-starting method of asynchronous motor under the wideband power supply is characterized in that taking following steps:
A. detect Ua, Ub, Uc synchronizing signal;
B. calculate the generating frequency of alternating current generator;
C. calculate the half wave cycles Ta of three-phase alternating voltage, Ta is full ON time;
D. detect the output current effective value of alternating current generator;
E. maximum current limit value is controlled through the slope, draws the output current limit value, and with output current effective value feedback ratio, its difference is handled through the PID adjuster, draws thyristor ON time Ton, the maximum of Ton is Ta;
F. confirm that according to synchronizing signal, Ta, Ton each thyristor conducting constantly;
G. according to the conducting of each thyristor constantly and ON time, generate each thyristor start pulse signal, control the conducting of each thyristor and close;
H. calculate corresponding asynchronous motor synchronous speed under current generating frequency;
I. detect the actual speed of asynchronous motor;
J. synchronous speed and the actual speed with asynchronous motor compares, if speed discrepancy greater than the speed discrepancy set point, then returns step a; Otherwise, get into next step;
K. soft start finishes, and closed major loop bypass contactor transfers direct driving to.
2. the current-limiting soft-starting method of asynchronous motor under the wideband power supply according to claim 1 is characterized in that taking following steps:
A. confirm maximum frequency division progression and corresponding divider ratio at different levels;
B. the frequency divider stage counter is initialized as 1;
C. confirm corresponding divider ratio according to frequency divider stage counter value;
D. carry out above-mentioned a to j step, wherein: in step f, be constantly and ON time, generate each thyristor gating half-wave start pulse signal, control the conducting of each thyristor and close according to the conducting of the corresponding half-wave of current frequency division gating and each thyristor; In step h, be to calculate pairing asynchronous motor synchronous speed under current generating frequency and crossover frequency; In step j,, then get into step e if speed discrepancy is not more than the speed discrepancy set point;
If E. current frequency divider stage counter value is less than maximum frequency division progression, then frequency divider stage counter value adds 1, returns C; Otherwise, get into above-mentioned steps k.
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| CN101862882A (en) * | 2010-05-11 | 2010-10-20 | 唐山松下产业机器有限公司 | Thyristor welder and control method and control device thereof |
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| CN104868795B (en) * | 2015-05-28 | 2017-07-07 | 中国铁路总公司 | Railway locomotive cooling fan motor method for starting-controlling |
| JP6121602B1 (en) * | 2016-07-20 | 2017-04-26 | 巴工業株式会社 | Start-up method of three-phase induction motor and decanter type centrifugal separator |
| CN107769662B (en) * | 2017-11-13 | 2020-04-21 | 苏州艾克威尔科技有限公司 | Control method of asynchronous motor |
| CN107659212A (en) * | 2017-11-13 | 2018-02-02 | 苏州艾克威尔科技有限公司 | The soft start control method of asynchronous machine |
| CN111211710B (en) * | 2020-02-24 | 2022-04-05 | 杭州九阳小家电有限公司 | Direct current motor control method of food processor and food processor |
| CN112858714B (en) * | 2020-12-31 | 2022-07-08 | 沈阳科网通信息技术有限公司 | Soft calculation method for rotating speed of asynchronous motor |
| CN113934243B (en) * | 2021-10-11 | 2022-05-31 | 上海希形科技有限公司 | Temperature equalization control method and system for parallel thyristors |
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| CN1250511A (en) * | 1997-03-11 | 2000-04-12 | 罗伯特·博施有限公司 | Gearbox-integrated electric machine for motor vehicle internal combustion engines and its control |
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| CN1653262A (en) * | 2002-05-10 | 2005-08-10 | 西门子西屋电力公司 | Methods for starting a combustion turbine and combustion turbine generator configured to implement same methods |
| CN2733739Y (en) * | 2004-03-24 | 2005-10-12 | 张世武 | Controller of dual closed-loop AC voltage-regulating speed-regulating device for blower fan water pump |
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- 2009-09-25 CN CN2009101876661A patent/CN101662247B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1250511A (en) * | 1997-03-11 | 2000-04-12 | 罗伯特·博施有限公司 | Gearbox-integrated electric machine for motor vehicle internal combustion engines and its control |
| CN2532610Y (en) * | 2002-03-20 | 2003-01-22 | 清华泰豪科技股份有限公司 | Permanent magnet synchronous motor |
| CN1653262A (en) * | 2002-05-10 | 2005-08-10 | 西门子西屋电力公司 | Methods for starting a combustion turbine and combustion turbine generator configured to implement same methods |
| CN2733739Y (en) * | 2004-03-24 | 2005-10-12 | 张世武 | Controller of dual closed-loop AC voltage-regulating speed-regulating device for blower fan water pump |
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